Air to fuel:Direct capture of CO_(2)from air and in-situ solar-driven conversion into syngas via Ni_(x)/NaA nanomaterials

Ever-increasing CO_(2)emissions and atmospheric concentration mainly due to the burning of traditional fossil fuels have caused severe global warming and climate change problems.Inspired by nature’s carbon cycle,we propose a novel dual functional catalyst-sorbent to tackle energy and environmental problems simultaneously via direct capture of CO_(2)from air and in-situ solar-driven conversion into clean fuels.Economically and operationally advantageous,the planned coupling reaction can be carried out in a single reactor without the requirement for an extra trapping device.The great CO_(2)capture and conversion performance in an integrated step is shown by the CO_(2)capacity of up to 0.38 mmol·g^(−1)for adsorption from 500 ppm CO_(2)at 25℃and the CO_(2)conversion rate of up to 95%.Importantly,the catalyst-sorbent is constituted of a nonprecious metal Ni catalyst and an inexpensive commercially available CO_(2)sorbent,viz,zeolite NaA.Furthermore,this designed dual functional material also exhibits outstanding stability performance.This work offers a novel pathway of capturing CO_(2)in the air at room temperature and converting it by CH4 into fuel,contributing to the new era of carbon neutrality.

Thermal Feature Analysis of a New Hot-Air Anti-Icing Structure

Ice accretion on surfaces of the aircraft and engine is a serious threat to the flight safety.In this paper,a novel hot air anti-icing method is proposed based on the porous foam.Taking the NACA0012 airfoil as an example,the traditional thermal protection structure is proved to exist the deficiency in balancing the heat exchange caused by route loss of the heat.By dividing the hot chamber into multiple regions to fill with various foam metal,flow resistance characteristics and heat transfer characteristics for this protection mode are analyzed in order to derive the maximized benefit in anti-icing process.The calculation results reveal that,under the same condition,the region filled with foamed copper not only improves the temperature uniformity on the anti-icing area,but also achieves a better protection effect for enhancing heat transfer between the tube and the hot gas,averagely above 20℃higher than it without porous foam filling in surface temperature.Additionally,the minimum mass flow rate of the protection hot air is reduced by 16.7%.The gratifying efficiency of the porous filler in fortifying heat transfer confirms the potential of replacing the efficient but complex heat transfer design with simple structure filled with foam metal.

Artificial“honeycomb-honey”decorated with non-noble plasmonic nanoparticles for superior solar capture and thermal energy storage

Phase change materials(PCMs)are popular solutions to tackle the unbalance of thermal energy supply and demand,but suffer from low thermal conductivity and leakage problems.Inspired by how honeybees store honey,we propose artificial“honeycombhoney”for excellent solar and thermal energy storage capacity based on TiN nanoparticles decorated porous AlN skeletonsPCMs composites.The thermal conductivity of composites achieves 21.58 W/(m·K)at AlN loading of 20 vol.%,superior to the state-of-the-art ceramic-based composites.The charging/discharging time is reduced to about half of pure PCMs with shapestability and thermal reliability well maintained over 500 melting/freezing cycles.The underlying mechanism can be attributed to the combination of single-crystal AlN whiskers with few crystal defects and reduced phonon scattering,as well as vertically arranged three-dimantional(3D)heat conduction channels.A rapid and efficient solar thermal storage is also demonstrated with solar thermal storage efficiency achieving a high value of 92.9%without employing additional spectrum selective coatings.This is benefited from high thermal conductivity and full-spectrum solar absorptance of up to 95%induced by plasmonic resonances of TiN nanoparticles.In addition,by embedding LiNO3-NaCl eutectics,the phase change enthalpy of composites reaches as high as 208 kJ/kg,making high energy storage density and fast energy storage rate compatible.This work offers new routes to achieve rapid,efficient,stable,and compact solar capture and thermal energy storage.

Granular porous calcium carbonate particles for scalable and high-performance solar-driven thermochemical heat storage

Calcium carbonate is promising thermochemical heat storage material for next-generation solar power systems due to its high energy storage density,low cost,and high operation temperature.Researchers have tried to improve energy storage performances of calcium carbonate recently,but most researches focus on powders,which are not suitable for scalable applications.Here,novel granular porous calcium carbonate particles with very high solar absorptance,energy storage density,abrasive resistances,and energy storage rate are proposed for direct solar thermochemical heat storage.The average solar absorptance is improved by 234%compared with ordinary particles.Both cycle stability and abrasive resistances are excellent with almost no decay of energy storage density over 25 cycles nor apparent particle weight loss over 24 h of continuous operation insides a planetary ball mill.In addition,the decomposition temperature is reduced by 2.8%–5.6%while the reaction rate of heat storage is enhanced by 80%–205%depending on the CO_(2) partial pressure.The decomposition process of doped granular porous CaCO_(3) particles is found to involve three overlapping processes.This work provides new routes to achieve scalable direct solar thermochemical heat storage for next-generation high-temperature solar power systems.

Current dilemma in photocatalytic CO_(2) reduction:real solar fuel production or false positive outcomings?

Solar driven carbon dioxide(CO_(2))recycling into hydrocarbon fuels using semiconductor photocatalysts offers an ideal energy conversion pathway to solve both the energy crisis and environmental degradation problems.However,the ubiquitous presence of carbonaceous contaminants in photocatalytic CO_(2) reduction system and the inferior yields of hydrocarbon fuels raise serious concerns about the reliability of the reported experimental results.Here in this perspective,we focus on the accurate assessment of the CO_(2) reduction products,systemically discuss the possible sources of errors in the product quantification,elaborate the common mistakes spread in the analysis of reaction products obtained in 13CO_(2) labelling experiments,and further propose reliable protocols for reporting the results of these isotopic tracing experiments.Moreover,the challenges and cautions in the precise measurement of O_(2) evolution rate are also depicted,and the amplification of the concentration of O_(2) in photoreactors well above the limit of detection is still demonstrated to be the most effective solution to this troublesome issue.We hope the viewpoints raised in this paper will help to assessment the reliability of the reported data in future,and also benefit the beginners that intend to dive in the photocatalytic CO_(2) reduction area.